1. Field
The invention relates generally to control of communication devices in a communication system, and more specifically to data transfer over a voice channel of the communication channel.
2. Background
Enhancements to communication devices are being developed and it may be desirable, or necessary, to change the operating mode of the communication device to utilize the enhancements. The operating mode of a communication device may be changed by transmitting initiating data to the communication device requesting that the communication device change its operating mode.
A technique that could be used to transmit the initiating data to change the operational mode of a destination communication device, is to transmit the initiating data over a voice channel. Typically, a user at the initiating device would use the device's keypad to enter the initiating data as a data sequence formatted as FSK or DTMF tones The tones are then encoded by a vocoder, a device used to encode and decode speech, and data corresponding to the tones are transmitted to the destination communication device.
In a destination device, a host processor receives the data corresponding to the sequence of tones and sends the data to a vocoder that decodes the tones. The tones are then converted back into the initiating data and the host processor determines that a special (changed) operational mode is desired by the initiating device. In response, the host processor of the destination device changes its operational mode and sends a message to the initiating device that will confirm the changed operational mode and will result in both devices operating in the desired mode. This technique may be used, for example, when two users want to communicate using a secure connection to transfer encrypted data.
A problem with this technique is that vocoders are optimized for encoding speech and are not well adapted to encode and decode pure tones such as would be used in data formatted as FSK or DTMF data. Also, the vocoder encoded data may be decoded and re-encoded as the data traverses a voice channel of a communication system. These, as well as other, problems lead to ineffective, and unreliable, transmission of the initiating data over the voice channel.
A technique used to transfer text messages across a communication system is Short Message Service (SMS). SMS is a service that enables the transmission of text messages between wireless communication devices (WCD). However, SMS is not supported in all networks. In addition, SMS messages are not used to transmit data to change the operational mode of a device, instead when the message is received it is simply displayed to the user. In addition, SMS messages are routed through a SMS center thereby adding delay in the signal arriving at the destination device.
There is therefore a need in the art for transmitting data that is used to change the operational mode of a communication device when the WCD is operating in a voice service option mode.